I am not sure when this will be fixed.
when you are on the forum at the top is notifications. when you click this you can see if anyone has sent you a private message. I will send you one.
Pm is short for private message. From your profile you can send a vistor message, like you just sent me. Everyone can see and read these conversations.
when you send a private message(PM) no one can see the message. Just you and the person you send it to.